ORAU Team 

Dose Reconstruction Project for NIOSH

Technical Information Bulletin: Savannah River Site 

Tritium Dose Assignment 

Document Number: 

ORAUT-OTIB-0003 

Effective Date: 10/03/2003 

Revision No.:00 

Controlled Copy No.: _________ 

Page 1 of 6 

Subject Expert: Fred Duncan 

Document Owner 

Approval: Signature on File Date: 09/29/2003

 James P. Griffin, Task 5 Manager 

Concurrence: Signature on File Date: 09/30/2003

 Richard E. Toohey, Project Director 

Approval: Signature on File Date: 10/03/2003

 James W. Neton, OCAS Health Science Administrator 

Supersedes: 

None 

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE 

EFFECTIVE 

DATE 

REV. 

NO. DESCRIPTION 

Draft 09/23/2003 00-A 

New document to provide guidance on the 

assignment of tritium dose for dose reconstructions 

at the Savannah River Site. Initiated by Fred 

Duncan. 

10/03/2003 10/03/2003 00 Approved Issue of Revision 00. Initiated by Fred 

Duncan. 
Date: 10/03/2003 Revision No. 00 Document No. ORAUT-OTIB-0003 Page 2 of 6 

PURPOSE 

 This Technical Information Bulletin provides guidance on the assignment of tritium or 

H-3 dose for dose reconstructions at the Savannah River Site (SRS), and is based on 

information provided in the Technical Basis Document for the Savannah River Site to 

be used for EEOICPA Dose Reconstructions, ORAUT-TKBS-0003 Rev. 01. 

1.0 BACKGROUND

At the SRS, the whole body dose equivalent for tritium was evaluated from urinary 

excretion of tritiated water and was typically added to the whole body dose equivalent 

from external sources. As discussed in ORAUT-TKBS-0003 Rev. 01, the minimum 

detectable activities (MDA) and reporting levels for tritium have decreased several 

times since start-up in 1953. The MDA was initially 1 μCi/L, and has decreased over 

time to the current level of 0.02 μCi/L. Similarly the reporting level has dropped from 1 

μCi/L to 0.1 μCi/L (ORAUT 2003). Additional guidance on assignment of tritium dose 

was needed to address the changing MDAs and reporting levels, along with the 

specific information recorded in radiological records for each case. 

3.0 GUIDANCE

Flowcharts that provide the logic for the assignment of tritium dose are presented in 

Figures 1 and 2. These apply to dose reconstructions at the SRS for the periods of 

1953 through 1983, and 1984 to the present, respectively. Decision criteria are provide 

to identify when it is appropriate to: use tritium doses as recorded in individual case 

records; assign tritium doses based on the potential missed dose (NIOSH 2002); or to 

evaluate the dose using recorded tritium bioassay results and internal dosimetry 

models. 
Date: 10/03/2003 Revision No. 00 Document No. ORAUT-OTIB-0003 Page 3 of 6 

Figure 1. SRS H-3 Dose Assignment Logic 

Result > 5uCi/L

in given year?

H-3 reported

with external

dose?

Have value for

assigned

dose?

Send to Internal

Dosimetry yes

yes

no

>missed dose? Assign missed

dose

No action needed

yes no

yes

Assume all results

> 5 accounted for

in reported dose

1<results<5? Assign missed

dose of 71 mrem

no

no

Multiply largest result

for calendar year by

1.946e-04 rem/d per

μCi/L times 365 d/yr to

obtain missed dose

yes

Any results <1? yes

No action

necessary; all

dose assumed

accounted for

no

1953-1983
Date: 10/03/2003 Revision No. 00 Document No. ORAUT-OTIB-0003 Page 4 of 6 

Figure 2. SRS H-3 Dose Assignment Logic 

Result > RL in

given year?

H-3 reported

with external

dose?

Have value for

assigned

dose?

Send to Internal

Dosimetry yes

yes

no

>missed dose? Assign missed

dose

No action needed

yes no

yes

Assume all results

> RL accounted for

in reported dose

Any

results<RL?

Assign missed dose

(1983-1992: 71 mrem;

1992-present: 7 mrem)

no

no

No action

necessary; all

dose assumed

accounted for

yes

1984-present
Date: 10/03/2003 Revision No. 00 Document No. ORAUT-OTIB-0003 Page 5 of 6 

4.0 DISCUSSION

4.1 SRS Dose Assignment Logic 1953-1983

For each year of covered employment at SRS during the period 1953 through 1983, 

tritium dose should be evaluated and assigned according to the flowchart in Figure 1. 

As reported in ORAUT-TKBS-0003 Rev. 01, only tritium bioassay results greater than 5 

μCi/L were evaluated prior to computer evaluation of data. It is believed that tritium 

results prior to 1984 were not evaluated by computer. For results that were evaluated, 

it is expected that tritium dose will be listed separately in the external dosimetry record 

and summed with the external dose 

Based on the above, the first decision criterion is whether there are tritium bioassay 

results greater than 5 μCi/L for a given year. If there are results greater than 5 μCi/L 

for a given year and external dosimetry records do not include the H-3 dose for that 

year, then the tritium dose needs to be evaluated and assigned by the Internal 

Dosimetry Group. If there are results greater than 5 μCi/L for a given year and a tritium 

dose is recorded in external dosimetry records, then the greater of the recorded dose 

or the missed dose is assigned for the dose reconstruction. 

If it is not clear what tritium dose was assigned in the radiological record, it is assumed 

that any results greater than the recording level were included in the tritium dose 

assessment. A missed dose is assigned based on the remaining results. If all tritium 

results are less than 1 μCi/L for a given year, then the missed dose of 0.071 rem is 

assigned. If there are any results between 1 μCi/L and 5 μCi/L then multiply the 

largest result for the calendar year by 1.946e-04 rem/day per μCi/L times 365 

days/year to obtain the missed dose 

4.2 SRS Dose Assignment Logic 1984 - Present

The flowchart for the period 1984 through the present is presented in Figure 2 and is 

similar to that for the preceding period; however, the first decision criterion is whether 

there are tritium bioassay results greater than the reporting level (instead of 5 μCi/L) for 

a given year. Reporting levels are assumed to be 1 μCi/L for the period 1984 to 1991, 

and 0.1 μCi/L for the period 1992 to the present. 

If there are results greater than the reporting level for a given year and external 

dosimetry records do not include the H-3 dose for that year, then the tritium dose 

needs to be evaluated and assigned by the Internal Dosimetry Group. If there are 

results greater than the reporting level for a given year and a tritium dose is recorded in 

external dosimetry records, then the greater of the recorded dose or the missed dose is 

assigned for the dose reconstruction. 

If it is not clear what tritium dose was assigned in the radiological record, it is assumed 

that any results greater than the reporting level were included in the tritium dose 

assessment. A missed dose is assigned based on the remaining results. If all tritium 

results are less than the reporting level for a given year, then a missed dose of 0.071 

rem is assigned for the period 1984 to 1991, and 0.007 rem is assigned for the period 

1992 to the present. 
Date: 10/03/2003 Revision No. 00 Document No. ORAUT-OTIB-0003 Page 6 of 6 

4.3 REFERENCES

ORAUT 2003. Technical Basis Document for the Savannah River Site to be used for 

EEOICPA Dose Reconstructions, ORAUT-TKBS-0003 Rev. 01. August, 21, 2003. Oak 

Ridge Associated Universities Team, Oak Ridge, Tennessee. 

NIOSH 2002. Internal Dose Reconstruction Implementation Guideline, OCAS-IG-002,

Rev 0. National Institute for Occupational Safety and Health, Cincinnati, Ohio